All of these are disadvantages of online surveys except which?

Multiple Choice

Some potential respondents have a pop$-$up blocker that prohibits a browser from opening a separate window that contains the survey.

Some potential respondents may employ spam blockers.

Email surveys may be viewed as junk.

The cost to set up and administer them is high.

Without the necessary technology, respondents can complete the survey multiple times, creating a significant blas in the results.